All three games in the series focus on the adventures of Gabriel Knight, a New Orleans author and bookstore owner who finds that his destiny is to become a Schattenjäger, or "Shadow Hunter". Gabriel's assistant, sidekick, and sometime romantic interest Grace Nakimura is a major supporting character in Sins of the Fathers. In The Beast Within and Blood of the Sacred, Blood of the Damned, she shares the role of protagonist with Gabriel. The player alternates between Gabriel and Grace for different portions of the latter two games.

The first episode of the series was released in 1993. Its story unfolds over a sequence of "days", each of which has a required set of actions to be performed before proceeding to the next. In this way, the game proceeds mostly linearly, since the puzzles on a given "day" must be completed in order to reach the next day. However, within each day play may be nonlinear. A similar format was used throughout the series, with "days" replaced by "chapters" and "time blocks" in the later games. Each game also awards a number of "points" both for completing game required actions and for completing various optional puzzles along the way.

Gabriel Knight: Sins of the Fathers and Gabriel Knight 3: Blood of the Sacred, Blood of the Damned both included, along with the game media and documentation, graphic novels that contained back-story to the starting points in either game, much in the tradition of Infocom's "feelies". The Sins of the Fathers graphic novel follows the story of Günter Ritter, an ancestor of Gabriel Knight, who has left his ancestral home for the American continent in the 17th century. The Blood of the Sacred, Blood of the Damned graphic novel details the events immediately preceding the player's starting point in the game.

After the release of Blood of the Sacred, Blood of the Damned, Jane Jensen stated that she had started planning a possible story and setting for a fourth game. A search of the SIDNEY computer interface for "gk4" in Blood of the Sacred, Blood of the Damned brings up an entry on ghosts, which Jane Jensen has remarked would have been the antagonists in her outline for a fourth entry to the series.[2] However, no Gabriel Knight 4 has been announced. In August 2006, it was confirmed that Jane Jensen's next adventure game project would not be a new Gabriel Knight but the revival of Gray Matter,[3] a game which was released in German speaking territories in November 2010 and released internationally in February 2011.[4]

The first game in the series introduces Gabriel Knight, a financially struggling horror novelist based in New Orleans. Gabriel is following a series of homicides, dubbed "The Voodoo Murders" for their apparent voodoo overtones hoping to use the police investigation, led by Detective Mosely, as the basis of a new novel. However, as he draws deeper into the investigation, and his shop assistant Grace Nakimura performs historical research for him, Gabriel links the murder spree both to New Orleans' voodoo past and towards the beautiful and mysterious New Orleans socialite, Malia Gedde.

Gabriel also discovers connections between the case and a horrific recurring nightmare which has plagued him all of his life. His investigation brings him into contact with Wolfgang Ritter, a lost family relative in Germany. Wolfgang informs Gabriel that his family has an ancient heritage in investigating supernatural evil and that Gabriel himself has inherited the mantle of Schattenjäger, a sort of modern-day Inquisitor. Gabriel discovers that his nightmares are the result of a curse brought upon his family by one of his ancestors, and that only by embracing his calling and solving the Voodoo Murders can he undo it.

Gabriel travels to Germany and Africa, before returning to New Orleans to confront those responsible for the murders and his family's suffering. The climax ends with Gabriel choosing between love and forgiveness or fulfilling his duty, offering two different dénouements as a result.

The second game (also known as Gabriel Knight 2: The Beast Within) follows Gabriel on his second Schattenjäger case. A year after the events of Sins of the Fathers, he has moved to his ancestral home in Bavaria, Germany to write his new novel. The population of Rittersberg, the seat of the Schattenjägers, are well aware of his family's reputation and when word reaches them of what is reported to be a werewolf attack in Munich, they compel Gabriel to go and investigate. Gabriel is joined in Germany by Grace, once she learns that he has begun a new case and hasn't asked her to join him. Whilst Gabriel follows a trail from missing zoo wolves to a mysterious men's hunting club in Munich, Grace conducts research back in Rittersberg and around Bavaria. Her investigations lead her to the history of King Ludwig II, the composer Richard Wagner and a shadowy figure known as the Black Wolf. Eventually the links between the cases become clear, and Grace discovers that the person in the greatest danger has become Gabriel himself.

The game was created using techniques developed in Phantasmagoria, with the characters and many objects captured in real-time video against blue screen backgrounds and appearing on "virtual sets" consisting largely of photographic backgrounds. Although this technique has come in for much criticism from games makers and players alike, The Beast Within was generally well received with the quality of the script and some of the performances coming in for particular praise. Dean Erickson plays Gabriel Knight and Joanne Takahashi plays Grace Nakimura.

The Beast Within was originally going to be much longer. Its original design indicated eight chapters rather than the published six, including one that required the player to act as Ludwig II and hide the Lost Opera in his castles. However, according to game designer Jane Jensen, the game ran over budget (almost a million dollars over its original three million dollar budget) and the required material could therefore not be filmed. It would also have taken up to nine CD-ROMs to incorporate all the additional story (the release version of the game shipped on six). This helps explain why there is a great deal of plot exposition in some of the cutscenes; particularly in the transition from Chapter Five to Six.[5]

Four years after the events of the second game, Gabriel and Grace are asked by the exiled Prince of Albany to protect his newborn son from a centuries-old family threat that appears to be a group of vampires. Shortly afterwards, the boy is kidnapped and Gabriel follows the kidnappers to the mysterious French village of Rennes-le-Château. Gabriel's arrival coincides with that of a tour group whose members are all supposedly in town hunting for a legendary local treasure linked to the Knights Templar, the Cathars and potentially connected to the Holy Grail. Among the international tour group is Gabriel's old friend, Detective Mosely, from New Orleans. Gabriel's search leads him to investigate the members of the group and search the town. Grace arrives shortly afterwards and delves into the history of the area to try to find the connection between the kidnapping and the area's rich history. Together they uncover the truth behind an incredible mystery, stretching back to the birth of Jesus Christ.

A custom designed 3D engine, the G-Engine, was created to drive the game which allowed the player control of a free roaming camera to explore environments and to watch non-interactive sequences from any distance or angle. The creation of such an ambitious engine came at a price, however, and the game which was originally due for release in Summer 1998 didn't ship until Fall 1999 after changes in the design team and the decision to undertake a major rearchitecture of the engine halfway through production.[6] The detailed story was inspired in part by The Holy Blood and the Holy Grail book. Tim Curry also returned to voice Gabriel Knight.

Blood of the Sacred, Blood of the Damned received mixed reviews with the general gaming press being less enthusiastic about the game's merits than dedicated adventure gaming publications. As with the other games in the series, though, most reviews of the game cited Jane Jensen's story as a subject for praise. The game was profiled in an article on Old Man Murray in which the author uses a puzzle from the game to lambast the absurd puzzles of adventure games as a whole.[7] It is the last adventure game that was published by Sierra Entertainment.

The rights to Gabriel Knight are currently held by Activision, which acquired them after merging with former rights holder Vivendi Universal in 2008.[8] Jane Jensen has pitched new Gabriel Knight games to both Vivendi and Activision over the years.

In April 2012, Jensen launched a new studio, Pinkerton Road Studio, with the plan to make new Gabriel Knight style adventure games. She has stated in interviews that she hopes shipping a game with Pinkerton Road is a step in the right direction for getting the chance to make new Gabriel Knight games in the future.[9] In October 2013, Jane Jensen confirmed that a remake of Gabriel Knight: Sins of the Fathers is going to be released on Windows, OS X, iOS and Android on October 15, 2014.[10][11]

Gabriel Knight is the central protagonist of the series. Aside from his double duties as a novelist and supernatural investigator, Gabriel is also the proprietor of St. George's Rare Books in his hometown of New Orleans. Charismatic, sardonic, and intuitive, he has a way with women that has at times proven to impede the progress of his cases. When the series starts, Gabriel is a down on his luck author whose instinctive drive to solve a killing spree ultimately leads him to discover his family's ancient heritage as a line of the Schattenjäger (Shadow Hunters). Upon the conclusion of his first case, Gabriel moves to Bavaria to reluctantly take up his birthright. His next two cases as a Schattenjäger are chronicled in the second and third games of the series. By GK3 Gabriel has taken on the job of a Schattenjäger full-time. He is hired by Prince James of Albany (in the GK3 graphic novel) to protect his infant son, Charlie, from a group of vampires called "The Night Visitors", later revealed to be the "Adepts of the Holy Blood". Charlie is kidnapped as Gabriel becomes paralyzed (through unknown means). He follows the kidnappers to a train where he is knocked out, waking up at the Couiza station and making his way to Rennes-le-Château where he begins to investigate the area and tour-group staying at the Rennes Hotel. Eventually, it is revealed that Prince James is a blood-descendant of Jesus and Gabriel confronts the Adepts in the rebuilt, underground Temple of Solomon. In the aftermath of his battle with the demon Asmodeus and the death of Montreaux (the head-vampire), Gabriel, Mosely and Mesmi discover the body of Jesus that is then carried off by Emilio Baza through a shining portal. When Gabriel returns to the hotel he discovers that Grace has left for India. It is also revealed that Gabriel is a descendant of a Roman soldier who nailed Jesus to the cross, and who accepted the duties as Schattenjäger for himself and his descendants as penance. The Schattenjäger talisman and dagger being made by blessed steel turned to gold after having been touched to Jesus' lips while he was on the cross.[citation needed]

Franklin Mosely (voiced by Mark Hamill in the first game, and David Thomas in the third) is Gabriel's best friend. In Sins of the Fathers, Mosely works as a detective for the New Orleans Police Department. He dismisses the supernatural aspects of the Voodoo Murders that Gabriel is investigating, but as the facts of the case become undeniable, he proves to be a strong ally in helping to solve the case. In Blood of the Sacred, Blood of the Damned, Mosely has traveled to France to participate in a tour of Rennes-le-Château, which seems odd to Gabriel, who suspects that he is up to something. In this game, Mosely is a more comical character, and at times, Gabriel takes advantage of him for his own gain. However, Mosely is still a competent cop, and helps to investigate a crime scene, as well as accompanying Gabriel in the final dungeon. Mosely and Gabriel have a playfully antagonistic relationship, with Mosely often ending up as the butt of Gabriel's jokes. He harbors a secret crush for Grace, and takes offense at Gabriel's demeaning attitude towards her.[citation needed]

Gerde Hull (voiced by Mary Kay Bergman in the first game, and played by Andrea Martin in the second) is the caretaker at Gabriel's ancestral home, Schloss Ritter. When Gabriel first meets Gerde in Sins of the Fathers, she is an anxious, enthusiastic, and misguidedly optimistic young woman. Her eagerness to help Gabriel to find his great-uncle Wolfgang is indicative of her love for him, and after Wolfgang's death, she agrees to stay and help Gabriel for the sake of Wolfgang's memory. Still grieving at the time of The Beast Within, Gerde presents a marked sadness, and is hostile towards Grace, whom she thinks is trying to supplant her as Gabriel's research assistant. After eventually warming to Grace, the two women become allies in order to save Gabriel's life. Gerde does not appear in the third game, which is set in France.[citation needed]

The stories of Sins of the Fathers and The Beast Within were adapted into novels by Jane Jensen. The first is a straightforward adaptation of the events of the game, an approach which Jane Jensen decided, in retrospect, was not the most successful way of introducing Gabriel Knight to a literary audience. For the second novel she "threw the whole idea of the game away and started again from scratch."[17] Both books are out of print as of 2010. As part of her 2012 Kickstarter campaign to fund a new adventure game, Jensen offered both Gabriel Knight novels as ebooks to backers who pledge $50 or more.[1]

In 1998, Sierra released the title Gabriel Knight Mysteries: Limited Edition, which contains:

An 8-disc PC CD box of first two GK games and electronic manuals.

a 419-page novelization of Gabriel Knight: Sins of the Fathers (written by Jane Jensen and published by Roc in 1997).

a full soundtrack of The Beast Within: A Gabriel Knight Mystery.

a 33-page full-colour graphic novel of an event that takes place almost 200 years before the opening of Gabriel Knight: Sins of the Fathers (written by Jane Jensen, art direction by Nathan Gams and illustrated by Terese Nielsen). NB: This graphic novel was previously bundled with the original 1993 edition (both CD-ROM version and 3.5" Floppy disk version).

a 20-page full-colour graphic novel of an event that takes place days before the opening of the then-upcoming Gabriel Knight 3: Blood of the Sacred, Blood of the Damned (written by Jane Jensen and illustrated by Ron Spears).